- Email: [email protected]
Effect of primary posterior continuous curvilinear capsulorrhexis with posterior optic buttonholing on pilocarpine-induced IOL shift
ARTICLE
Effect of primary posterior continuous curvilinear capsulorrhexis with posterior optic buttonholing on pilocarpine-induced IOL shift Christina Leydolt, MD, Rupert Menapace, MD, Eva-Maria Stifter, MD, Ana Prinz, MD, Thomas Neumayer, MD
PURPOSE: To assess intraocular lens (IOL) shift along the visual axis induced by ciliary muscle contraction with pilocarpine after cataract surgery and to compare primary posterior continuous curvilinear capsulorrhexis (CCC) and posterior optic buttonholing with IOLs implanted in the bag. SETTING: Department of Ophthalmology, Medical University of Vienna, Vienna, Austria. DESIGN: Clinical trial. METHODS: Eyes with age-related cataract had cataract surgery with implantation of a nonaccommodating IOL (AF-1 YA-60BB). Surgery was performed with primary posterior CCC and posterior buttonholing in 1 eye (study eyes) and with conventional in-the-bag implantation in the contralateral eye (control eyes). After a minimum of 6 months postoperatively, the anterior chamber depth was assessed with partial coherence interferometry before and after application of pilocarpine 2.0% and, after a washout interval of 1 week, before and after the application of cyclopentolate 1.0%. RESULTS: Forty eyes of 20 patients were enrolled. A slight backward shift of the IOL (C78 mm) in study eyes and in control eyes (C118 mm) was detected after pilocarpine application (both P<.05). No significant difference in IOL shift was found between study eyes and control eyes (PZ.19). CONCLUSIONS: Combined primary posterior CCC and posterior optic buttonholing did not affect IOL shift during pharmacologically stimulated ciliary muscle contraction compared with in-thebag implanted IOLs. Capsule fibrosis diminished with primary posterior CCC but did not seem to be the only limiting factor in the accommodative IOL shift. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned. J Cataract Refract Surg 2012; 38:1895–1901 Q 2012 ASCRS and ESCRS
Restoration of accommodation in pseudophakic patients is a major goal of modern cataract surgery. Until now, a variety of devices and surgical techniques have been introduced to solve the problem of presbyopia correction and to provide satisfactory distance and near vision without spectacles after cataract surgery. An example is implantation of multifocal intraocular lenses (IOLs) that improve uncorrected near vision at the expense of reduced contrast sensitivity.1 Other surgical techniques, such as refilling the capsular bag with inflatable endocapsular balloons2 or in situ cured biocompatible silicone gels,3 led to promising early results in animal experiments but resulted in critical problems, such as capsule opacification. Varying outcomes have been reported with scleral expansion surgery,4,5 zonal photorefractive keratectomy,6 and decentered laser in Q 2012 ASCRS and ESCRS Published by Elsevier Inc.
situ keratomileusis7 for presbyopia correction, and these methods are still considered investigational. Since the introduction of so-called accommodating IOLs, a new generation of IOLs to correct presbyopia has been developed.8 Provided that the ciliary muscle maintains its potential for contraction with increasing age,9,10 the mechanism of these IOLs is based on the Helmholtz theory of accommodation,11 which hypothesizes that force is transmitted from the ciliary muscle to the lens via the zonular apparatus, or the hydraulic suspension theory of Coleman,12 which assumes that changes in vitreous pressure are responsible for changes in the lens shape. Currently available accommodating IOLs are designed to transform such forces of the ciliary muscle into a forward shift of the IOL optic, also referred to as the optic-shift concept. With 0886-3350/$ - see front matter http://dx.doi.org/10.1016/j.jcrs.2012.06.044
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this concept, a limiting factor of IOL shift seems to be capsule fibrosis and the consequent rigidity of the capsular bag, which thereby restricts axial IOL optic movement. Recently, the combination of primary posterior continuous curvilinear capsulorrhexis (CCC) with posterior optic buttonholing of the IOL was shown to be a safe procedure to prevent posterior capsule opacification and capsule fibrosis.13–19 Therefore, removing the posterior capsule should inherently reduce the constricting factor of the capsule and thus enhance the axial mobility of the IOL. The aim of this study was to assess IOL shift of a standard nonaccommodating IOL during pharmacologically stimulated ciliary muscle contraction in eyes with combined posterior CCC and posterior optic buttonholing and to compare it with the shift in eyes having conventional in-the-bag implantation of the same IOL. PATIENTS AND METHODS This randomized prospective controlled clinical trialA was performed at the Department of Ophthalmology, Vienna General Hospital. All research and measurements followed the tenets of the Declaration of Helsinki, and informed consent was obtained from all patients. The study was approved by the Ethics Committee, Medical University of Vienna. Inclusion criteria were bilateral age-related cataract and good overall physical constitution. Exclusion criteria were corneal astigmatism of 1.00 diopter (D) or more, a history of ocular trauma or intraocular surgery, laser treatment, diabetes mellitus requiring medical control, pseudoexfoliation syndrome, glaucoma, uveitis, and retinal pathology that would make a postoperative visual acuity of 20/40 (Z0.5) or better unlikely. Preoperative biometry was performed with the IOLMaster partial coherence interferometry (PCI) device (Carl Zeiss Meditec AG). All eyes received an AF-1 YA-60BB IOL (Hoya Medical Europe). This nonaccommodating 3-piece hydrophobic acrylic IOL has an optic diameter of 6.0 mm, an overall length of 12.5 mm, and modified C-loop poly(methyl methacrylate) (PMMA) haptics with 5 degrees of angulation. The IOL power was calculated using the SRK/T formula20 with an A constant of 118.8, as recommended by the IOL manufacturer. In myopic eyes with an axial eye length greater than 24.0 mm, the Holladay formula21 was applied. In hyperopic eyes with an axial eye length less than 22 mm, the Hoffer Q formula22,23 was used for IOL power calculation.
Submitted: April 17, 2012. Final revision submitted: June 20, 2012. Accepted: June 20, 2012. From the Department of Ophthalmology, Medical University of Vienna, Vienna, Austria. Corresponding author: Rupert Menapace, MD, Universit€atsklinik f€ ur Augenheilkunde, Allgemeines, Krankenhaus Wien, W€ahringer G€ urtel 18 – 20, A-1090 Vienna, Austria. E-mail: rupert. [email protected].
Cataract surgery with combined primary posterior CCC and posterior optic buttonholing followed by IOL implantation was performed in 1 eye (study eye) and conventional phacoemulsification cataract surgery with in-the-bag implantation of the IOL in the contralateral eye (control eye) in random order. The same surgeon (R.M.) performed all cataract surgeries in a standardized fashion between June 2006 and October 2006. The surgical technique with combined primary posterior CCC and posterior optic buttonholing has been described in detail.24–26 A temporal 3.0 posterior limbal incision was created. An anterior CCC, hydrodissection, and phacoemulsification of the nucleus were followed by coaxial cortical remnant aspiration and biaxial lens fiber peeling. The anterior segment was filled with sodium hyaluronate 1.0% (Healon) to allow the remaining peripheral anterior capsule to settle on the posterior capsule and flatten the central posterior capsule. As a result, the capsule fornix collapsed and both capsules formed a common flat diaphragm. Following the outlines of the anterior CCC, a well-centered 4.5 mm to 5.0 mm primary posterior CCC was created. After the central capsule flap was removed from the eye, the ophthalmic viscosurgical device (OVD) was gently injected beneath the peripheral ring of residual posterior capsule to separate it from the underlying vitreous surface. When this was completed along the entire circumference, the anterior segment was prepared for IOL implantation. The central chamber was deepened and the nasal capsule fornix extended with OVD to take up the leading IOL haptic. The tip of the leading IOL haptic was guided into the nasal capsular bag fornix, and the optic and trailing haptic were rotated into the bag. Using gentle downward pressure, the optic was entrapped in the primary posterior CCC. The OVD was then aspirated from the anterior chamber and capsular bag fornix using low flow and vacuum settings. As the posterior capsule was firmly pressed onto the anterior optic surface, the optic–capsule diaphragm hermetically sealed the posterior segment and no OVD was allowed to access the anterior chamber from the retrolental space during the maneuver. Next, the incisions were hydrated and the globe was pressurized. The eye was left unpatched. All patients received diclofenac sodium (Voltaren) and prednisolone acetate (Ultracortenol) eyedrops 4 times daily for 4 weeks postoperatively. The anterior chamber depth (ACD), defined as the distance from the posterior corneal surface to the anterior IOL surface, was measured after a minimum of 6 months postoperatively with the ACMaster (Zeiss Meditec AG) based on the principal of PCI biometry. The principle of the dual-beam version of PCI and its use in phakic and pseudophakic eyes has been described.27–29 This technique has been used to perform accurate biometry in pseudophakic eyes with a precision of 4 mm for measuring the ACD and an axial resolution of 10 mm.30–32 The PCI device measures the ACD parallel to the optical axis of the eye and is insensitive to longitudinal eye movements during measurements. The eye being measured is the fixating eye, which prevents interference from convergence movements during measurement. Baseline measurements were performed with the patient fixating on an internal target collimated to infinity with the eye being measured. The eye was measured with the patient fixating on the target at optical infinity; 5 ACD measurements were taken. To assess the effect of maximum ciliary muscle contraction, 2 drops of pilocarpine 2% were instilled into the conjunctival sac of the examined eye at 5-minute intervals. Thirty minutes after the first application, the ACD was measured again. After a washout period of 1 week, the ACD measurements were taken again under
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cycloplegic conditions using cyclopentolate 1%; the protocol of administration and measurements were identical to those for pilocarpine application. A previous study of another nonaccommodating 1-piece foldable IOL (Acrysof SA60AT, Alcon Laboratories, Inc.)33 found the standard deviation (SD) of pilocarpine-induced IOL movement to be 125 mm. For this variability, it was determined that a sample size of 18 eyes would be needed to detect IOL movement of 175 mm (approximately equivalent to 0.25 D refractive change in the spectacle plane) with a power of 80% at the 0.05 level of significance. To compare the means of the change in the ACD (baseline versus pilocarpine), the paired Student t test was used. The ACD and IOL movement data are presented as the median value G SD and range. The influence of baseline ACD and change in ACD (ie, IOL movement under pilocarpine) was assessed using the Pearson correlation analysis. A P value of 0.05 or less was considered statistically significant.
Table 1. Anterior chamber depth under different conditions.
ACD (mm) Baseline Median G SD Mean Range Pilocarpine Median G SD Mean Range Cyclopentolate Median G SD Mean Range
P Value
POBH
IB
4.864 G 0.347 4.788 4.211, 5.404
4.724 G 0.300 4.700 4.160, 5.140
.12
4.921 G 0.308 4.893 4.324, 5.427
4.869 G 0.356 4.811 4.149, 5.523
.77
4.904 G 0.303 4.879 4.398, 5.439
4.807 G 0.273 4.776 4.395, 5.192
.40
ACD Z anterior chamber depth; IB Z in the bag; POBH Z posterior optic buttonholing
RESULTS The study enrolled 40 eyes of 20 patients. The mean age of the 13 women (65%) and 7 men (35%) was 77 years G 8 (SD) (range 55 to 88 years). The mean postoperative follow-up was 9.1 G 1.4 month (range 6 to 10 months). One patient was excluded postoperatively because the PCI measurements under pilocarpine were not possible in the control eye for unknown reasons. No intraoperative complications occurred. The median postoperative spherical equivalent was 1.38 G 1.25 D (range 4.00 to 0.50 D) in study eyes and 1.13 G 1.22 D (range 3.88 to 0.25 D) in control eyes. There was no significant difference between the groups (PZ.13). The median target refraction was 0.64 G 1.21 D (range 3.98 to 0.26 D) in study eyes and 0.53 G 1.10 D (range 3.39 to 0.20 D) in control eyes. Table 1 shows the ACD measurements under the various conditions. There was no significant difference in the median postoperative ACD between study eyes and control eyes (PZ.12) (Figure 1). After application of pilocarpine, a statistically significant backward IOL shift was detected in both groups of eyes; the mean shift was C78 G 78 mm in study eyes and C118 G 117 mm in control eyes (both P!.05) (Figure 2). There was no significant difference in pilocarpine-induced IOL shift between the 2 groups of eyes (PZ.19). The ACD measurements under cyclopentolate showed almost no IOL movement in study eyes (mean C20 G 26 mm; PZ.54) or in control eyes (mean C23 G 46 mm; PZ.87) (PZ.83 between eyes). There was no significant correlation between baseline ACD and IOL shift under pilocarpine-induced ciliary muscle contraction (r2 Z 0.29, PZ.29 in study eyes; r2 Z 0.30, PZ0.27 in control eyes). DISCUSSION This study showed a slight significant backward IOL shift in eyes with primary posterior CCC and posterior
optic buttonholing during pharmacologically stimulated ciliary muscle contraction with pilocarpine. Compared with IOLs implanted in the bag, no significant difference in IOL shift was detected. In the past, studies of monofocal nonaccommodating and of so-called accommodating IOLs were performed to gain a better understanding of the interplay between the ciliary body–capsular bag–IOL during pseudophakic accommodation or to assess the accommodative potential of an IOL. With conventional IOLs, varying results after near stimulus–driven ciliary muscle stimulation or pharmacologic stimulation with pilocarpine have been reported. Using optical pachymetry, Hardman Lea et al.34 observed a maximum forward IOL shift of 0.25 mm induced by pilocarpine. Using ultrasound, _ 35 found a forward shift Lesiewska-Junk and Ka1uzny of 0.42 mm in young pseudophakic patients while
Figure 1. Anterior chamber depth at baseline. Boxes show the interquartile range, whiskers the minimum and maximum (IB Z in the bag; POBH Z posterior optic buttonholing).
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Figure 2. Pilocarpine-induced IOL shift in pseudophakic eyes after cataract surgery assessed with PCI. Positive values indicate a backward shift, negative values a forward shift of the IOL. Boxes show the interquartile range, whiskers the minimum and maximum (IB Z in the bag; IOL Z intraocular lens; POBH Z posterior optic buttonholing).
accommodating at near. In another study, Niessen et al.36 found a forward shift of 0.18 mm. However, the reproducibility of the measurement methods used in these studies was poor. Using the high-precision PCI method, we recently showed that a plate-haptic IOL (AA4203VF, Staar Surgical Co.) had slight forward movement ( 162 mm).37 The 3-piece IOLs did not shift forward but shifted slightly backward; the mean was 56 mm for the MC 220 PMMA IOL (Dr. Schmidt Intraocularlinsen GmbH), C37 mm for the AR40 Sensar IOL (Allergan, Inc.), and C156 mm for the Acrysof MA60BM IOL (Alcon Laboratories, Inc.).37 The 1-piece Acrysof SA60AT foldable IOL was found to shift slightly backward by C25 mm during pilocarpine-induced ciliary muscle contraction.33 With a 20.0 D optic IOL, axial optic movement of approximately 720 mm corresponds to a 1.00 D change in refraction38,39; thus, the shifts detected are too small to provide relevant accommodation. Currently available accommodating IOLs should transform the forces of the ciliary body during accommodation into a forward shift of the IOL optic (optic-shift concept). To achieve an accommodative amplitude of 2.90 D, which would result in a reading distance of 35 cm, an anterior IOL shift of 2.2 mm would be needed, assuming an IOL power of 20.00 D.40 Until now, 3 presumably accommodating IOLs have been commercially available: the Biocomfold (Morcher GmbH), the 1CU (Human Optics AG), and the AT-45 Crystalens (Eyonics, Inc.). Summarizing the results of several nonrandomized trials using pharmacologic stimulation of the ciliary muscle with pilocarpine, the IOL shift varied with different
measurement techniques. Most studies of the 1CU IOL41–45 and the Biocomfold IOL37 found a forward shift of less than 700 mm in nearly all patients, which equals less than 1.00 D of accommodative amplitude at the spectacle plane. The IOL shift results of the AT-45 Crystalens IOL are controversial (slight forward shift46,47 and minimal backward shift48). Only 4 randomized controlled studies that evaluated pilocarpine-induced IOL shift found that accommodating IOLs were associated with significantly greater anterior IOL shift than control monofocal IOLs (1CU: 370 mm,49 820 mm,50 220 mm;51 Biocomfold: 710 mm52). However, no study found forward movement of more than 1.0 mm and the amount of movement was variable among patients. One limiting factor of IOL shift during accommodation through force transmission from the ciliary muscle to the lens via the zonular fibers (Helmholtz theory11) or through changes in vitreous pressure (Coleman theory12) could be capsule fibrosis. The fibrosis stiffens the capsular bag, causing a “walled in” IOL and thereby restricting axial movement of the optic. Therefore, to minimize constricting fibrosis and to provide a more flexible IOL optic, a primary posterior CCC with consequent posterior optic buttonholing was performed in 1 eye in the present study. In our study, IOL shift was measured using PCI, which enables precise measurement of very small changes. As expected for a standard IOL design, the IOL shift was very small and variable between patients. There was no difference between eyes with posterior optic buttonholing (study eyes) and eyes with conventional in-the-bag IOL implantation (control eyes). There was a small backward shift of C78 mm in study eyes and C118 mm in control eyes under pilocarpine and of C20 mm and C23 mm, respectively, under cyclopentolate. Although we have shown previously that pilocarpine acts physiologically in young phakic subjects,53 it seems to be a super stimulus in presbyopic and pseudophakic subjects53,54 when comparing pilocarpine-induced accommodation with voluntary near-point fixation. Therefore, although IOL movement may be overestimated with pilocarpine use, pilocarpine is still useful in the evaluation of the accommodative potential of an IOL. The same direction of shift found with ciliary muscle contraction and relaxation was previously observed with other IOLs37 and could possibly be explained by the fact that the IOL is in a slightly posterior vaulted configuration after completion of capsular bag shrinkage or in the posterior optic buttonholing position, respectively. Under pilocarpine-induced ciliary muscle contraction, there may be some direct pressure of the ciliary body on the haptic ends, causing increased vaulting that pushes the optic backward concomitant
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with a slight forward movement of the apex of the ciliary muscle. This would result in a net slight backward movement of the optic. Under cyclopentolate, the ciliary muscle apex rotates backward, causing the entire IOL–capsule complex to move backward. The backward IOL shift in both groups under pharmacologic stimulation of accommodation also reflects the failure of the optic-shift principle in providing clinically significant IOL movement in pseudophakic eyes (inconsistence of the hydraulic suspension theory of accommodation of Coleman12). The negligible small amount of mean IOL shift despite reduced fibrosis in the posterior optic buttonholing group shows that no optic shift movement during accommodation can be expected with this technique. This is consistent with observations in a study by Cleary et al.55 in which another fibrosisreducing procedure, the bag-in-the-lens concept, also led to an insignificant small forward IOL shift during pilocarpine stimulation. The more pronounced backward movement of the IOL in the posterior optic buttonholing group led to a (clinically irrelevant) disaccommodation compared with that of conventional in-the-bag fixated IOLs. However, the IOLs in this study are nonaccommodating; using accommodating IOLs with a specific design and haptics with flexible hinges may have led to a more pronounced IOL optic shift. To conclude, pilocarpine-induced ciliary muscle contraction after implantation of a nonaccommodating 3-piece IOL after cataract surgery with combined posterior capsulorrhexis and posterior optic buttonholing led to a slight significant backward IOL shift and thus to disaccommodation. The detected IOL shift did not differ significantly from the shift of in-the-bag IOLs. WHAT WAS KNOWN Accommodating IOLs based on the focus-shift principle and designed to provide good distance, intermediate, and near visual acuity have not shown clinically relevant movement during pilocarpine-induced ciliary muscle stimulation. The removal of the posterior capsule with a primary posterior CCC combined with posterior optic buttonholing was found to reduce capsule fibrosis, which is considered to limit axial IOL movement. WHAT THIS PAPER ADDS Posterior optic buttonholing of a 3-piece IOL showed no accommodative advantage over a conventional in-thebag fixation. This provides further evidence that the axial IOL optic movement is insignificant and fails to produce significant focus-shift-induced accommodation.
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flexible implants. Br J Ophthalmol 1990; 74:22–25; Available at: http://www.ncbi.nlm.nih.gov/pmc/articles/ PMC1041972/pdf/brjopthal00575-0030.pdf. Accessed June 29, 2012 _ J. Intraocular lens movement and Lesiewska-Junk H, Ka1uzny accommodation in eyes of young patients. J Cataract Refract Surg 2000; 26:562–565 Niessen AGJE, de Jong LB, van der Heijde GL. Pseudo-accommodation in pseudophakia. Eur J Implant Refract Surg 1992; 4:91–94 Findl O, Kiss B, Petternel V, Menapace R, Georgopoulos M, Rainer G, Drexler W. Intraocular lens movement caused by ciliary muscle contraction. J Cataract Refract Surg 2003; 29:669–676 Olsen T, Gimbel H. Phacoemulsification, capsulorhexis, and intraocular lens power prediction accuracy. J Cataract Refract Surg 1993; 19:695–699 Haigis W, Trier HG. Linsenberechnungsformeln. In: Buschmann W, Trier HG, eds, Ophthalmologische Ultraschalldiagnostik. Berlin, German, Springer-Verlag, 1989; 75–80 Holladay JT. Refractive power calculations for intraocular lenses in the phakic eye. Am J Ophthalmol 1993; 116:63–66 Langenbucher A, Huber S, Nguyen NX, Seitz B, Gusek€chle M. Measurement of accommodation after Schneider GC, Ku implantation of an accommodating posterior chamber intraocular lens. J Cataract Refract Surg 2003; 29:677–685 € bel K, Guthoff R. Changes of the acSchneider H, Stachs O, Go commodative amplitude and the anterior chamber depth after implantation of an accommodative intraocular lens. Graefes Arch Clin Exp Ophthalmol 2006; 244:322–329 €chle M, Nguyen NX, Langenbucher A, Gusek-Schneider GC, Ku Seitz B, Hanna KD. Implantation of a new accommodative posterior chamber intraocular lens. J Refract Surg 2002; 18:208–216 Auffarth GU, Martin M, Fuchs HA, Rabsilber TM, Becker KA, € t der Vorderkammertiefenmessung zur Schmack I. Validita Akkommodations-evaluierung nach Implantation einer akkommodativen Intraokularlinse (Modell Humanoptics 1CU) [Validity of anterior chamber depth measurements for the evaluation of accommodation after implantation of an accommodative Humanoptics 1CU intraocular lens]. Ophthalmologe 2002; 99:815–819 Stachs O, Schneider H, Stave J, Guthoff R. Potentially accommodating intraocular lenses an in vitro and in vivo study using three-dimensional high-frequency ultrasound. J Refract Surg 2005; 21:37–45 Marchini G, Pedrotti E, Sartori P, Tosi R. Ultrasound biomicroscopic changes during accommodation in eyes with accommodating intraocular lenses; pilot study and hypothesis for the mechanism of accommodation. J Cataract Refract Surg 2004; 30:2476–2482 Stachs O, Schneider H, Beck R, Guthoff R. Pharmacological-induced haptic changes and the accommodative performance in patients with the AT-45 accommodative IOL. J Refract Surg 2006; 22:145–150 Koeppl C, Findl O, Menapace R, Kriechbaum K, Wirtitsch M, Buehl W, Sacu S, Drexler W. Pilocarpine-induced shift of an accommodating intraocular lens: AT-45 Crystalens. J Cataract Refract Surg 2005; 31:1290–1297 Findl O, Kriechbaum K, Menapace R, Koeppl C, Sacu S, Wirtitsch M, Buehl W, Drexler W. Laserinterferometric assessment of pilocarpine-induced movement of an accommodating intraocular lens; a randomized trial. Ophthalmology 2004; 111:1515–1521 Sauder G, Degenring RF, Kamppeter B, Hugger P. Potential of the 1 CU accommodative intraocular lens. Br J Ophthalmol 2005; 89:1289–1292. Available at: http://www.ncbi.nlm.nih. gov/pmc/articles/PMC1772858/pdf/bjo08901289.pdf. Accessed June 29, 2012
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51. Hancox J, Spalton D, Heatley C, Jayaram H, Marshall J. Objective measurement of intraocular lens movement and dioptric change with a focus shift accommodating intraocular lens. J Cataract Refract Surg 2006; 32:1098–1103 52. Legeais J-M, Werner L, Werner L, Abenhaim A, Renard G. Pseudoaccommodation: BioComFold versus a foldable silicone intraocular lens. J Cataract Refract Surg 1999; 25:262–267 53. Koeppl C, Findl O, Kriechbaum K, Drexler W. Comparison of pilocarpine-induced and stimulus-driven accommodation in phakic eyes. Exp Eye Res 2005; 80:795–800 54. Kriechbaum K, Findl O, Koeppl C, Menapace R, Drexler W. Stimulus-driven versus pilocarpine-induced biometric changes in pseudophakic eyes. Ophthalmology 2005; 112:453–459 55. Cleary G, Spalton DJ, Gala KB. A randomized intraindividual comparison of the accommodative performance of the bag-inthe-lens intraocular lens in presbyopic eyes. Am J Ophthalmol 2010; 150:619–627
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OTHER CITED MATERIAL A. Menapace R. Cataract surgery with combined primary posterior continuous curvilinear capsulorhexis (PPCCC) and posterior buttonholing (POBH) in comparison to conventional in the bag intraocular lens (IOL) implantation. ISRCTN35593439, 2007. Available at: http://www.controlled-trials.com/isrctn/pf/ 35593439. Accessed July 3, 2012
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First author: Christina Leydolt, MD Department of Ophthalmology, Medical University of Vienna, Austria
Effect of primary posterior continuous curvilinear capsulorrhexis with posterior optic buttonholing on pilocarpine-induced IOL shift Christina Leydolt, MD, Rupert Menapace, MD, Eva-Maria Stifter, MD, Ana Prinz, MD, Thomas Neumayer, MD
PURPOSE: To assess intraocular lens (IOL) shift along the visual axis induced by ciliary muscle contraction with pilocarpine after cataract surgery and to compare primary posterior continuous curvilinear capsulorrhexis (CCC) and posterior optic buttonholing with IOLs implanted in the bag. SETTING: Department of Ophthalmology, Medical University of Vienna, Vienna, Austria. DESIGN: Clinical trial. METHODS: Eyes with age-related cataract had cataract surgery with implantation of a nonaccommodating IOL (AF-1 YA-60BB). Surgery was performed with primary posterior CCC and posterior buttonholing in 1 eye (study eyes) and with conventional in-the-bag implantation in the contralateral eye (control eyes). After a minimum of 6 months postoperatively, the anterior chamber depth was assessed with partial coherence interferometry before and after application of pilocarpine 2.0% and, after a washout interval of 1 week, before and after the application of cyclopentolate 1.0%. RESULTS: Forty eyes of 20 patients were enrolled. A slight backward shift of the IOL (C78 mm) in study eyes and in control eyes (C118 mm) was detected after pilocarpine application (both P<.05). No significant difference in IOL shift was found between study eyes and control eyes (PZ.19). CONCLUSIONS: Combined primary posterior CCC and posterior optic buttonholing did not affect IOL shift during pharmacologically stimulated ciliary muscle contraction compared with in-thebag implanted IOLs. Capsule fibrosis diminished with primary posterior CCC but did not seem to be the only limiting factor in the accommodative IOL shift. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned. J Cataract Refract Surg 2012; 38:1895–1901 Q 2012 ASCRS and ESCRS
Restoration of accommodation in pseudophakic patients is a major goal of modern cataract surgery. Until now, a variety of devices and surgical techniques have been introduced to solve the problem of presbyopia correction and to provide satisfactory distance and near vision without spectacles after cataract surgery. An example is implantation of multifocal intraocular lenses (IOLs) that improve uncorrected near vision at the expense of reduced contrast sensitivity.1 Other surgical techniques, such as refilling the capsular bag with inflatable endocapsular balloons2 or in situ cured biocompatible silicone gels,3 led to promising early results in animal experiments but resulted in critical problems, such as capsule opacification. Varying outcomes have been reported with scleral expansion surgery,4,5 zonal photorefractive keratectomy,6 and decentered laser in Q 2012 ASCRS and ESCRS Published by Elsevier Inc.
situ keratomileusis7 for presbyopia correction, and these methods are still considered investigational. Since the introduction of so-called accommodating IOLs, a new generation of IOLs to correct presbyopia has been developed.8 Provided that the ciliary muscle maintains its potential for contraction with increasing age,9,10 the mechanism of these IOLs is based on the Helmholtz theory of accommodation,11 which hypothesizes that force is transmitted from the ciliary muscle to the lens via the zonular apparatus, or the hydraulic suspension theory of Coleman,12 which assumes that changes in vitreous pressure are responsible for changes in the lens shape. Currently available accommodating IOLs are designed to transform such forces of the ciliary muscle into a forward shift of the IOL optic, also referred to as the optic-shift concept. With 0886-3350/$ - see front matter http://dx.doi.org/10.1016/j.jcrs.2012.06.044
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this concept, a limiting factor of IOL shift seems to be capsule fibrosis and the consequent rigidity of the capsular bag, which thereby restricts axial IOL optic movement. Recently, the combination of primary posterior continuous curvilinear capsulorrhexis (CCC) with posterior optic buttonholing of the IOL was shown to be a safe procedure to prevent posterior capsule opacification and capsule fibrosis.13–19 Therefore, removing the posterior capsule should inherently reduce the constricting factor of the capsule and thus enhance the axial mobility of the IOL. The aim of this study was to assess IOL shift of a standard nonaccommodating IOL during pharmacologically stimulated ciliary muscle contraction in eyes with combined posterior CCC and posterior optic buttonholing and to compare it with the shift in eyes having conventional in-the-bag implantation of the same IOL. PATIENTS AND METHODS This randomized prospective controlled clinical trialA was performed at the Department of Ophthalmology, Vienna General Hospital. All research and measurements followed the tenets of the Declaration of Helsinki, and informed consent was obtained from all patients. The study was approved by the Ethics Committee, Medical University of Vienna. Inclusion criteria were bilateral age-related cataract and good overall physical constitution. Exclusion criteria were corneal astigmatism of 1.00 diopter (D) or more, a history of ocular trauma or intraocular surgery, laser treatment, diabetes mellitus requiring medical control, pseudoexfoliation syndrome, glaucoma, uveitis, and retinal pathology that would make a postoperative visual acuity of 20/40 (Z0.5) or better unlikely. Preoperative biometry was performed with the IOLMaster partial coherence interferometry (PCI) device (Carl Zeiss Meditec AG). All eyes received an AF-1 YA-60BB IOL (Hoya Medical Europe). This nonaccommodating 3-piece hydrophobic acrylic IOL has an optic diameter of 6.0 mm, an overall length of 12.5 mm, and modified C-loop poly(methyl methacrylate) (PMMA) haptics with 5 degrees of angulation. The IOL power was calculated using the SRK/T formula20 with an A constant of 118.8, as recommended by the IOL manufacturer. In myopic eyes with an axial eye length greater than 24.0 mm, the Holladay formula21 was applied. In hyperopic eyes with an axial eye length less than 22 mm, the Hoffer Q formula22,23 was used for IOL power calculation.
Submitted: April 17, 2012. Final revision submitted: June 20, 2012. Accepted: June 20, 2012. From the Department of Ophthalmology, Medical University of Vienna, Vienna, Austria. Corresponding author: Rupert Menapace, MD, Universit€atsklinik f€ ur Augenheilkunde, Allgemeines, Krankenhaus Wien, W€ahringer G€ urtel 18 – 20, A-1090 Vienna, Austria. E-mail: rupert. [email protected].
Cataract surgery with combined primary posterior CCC and posterior optic buttonholing followed by IOL implantation was performed in 1 eye (study eye) and conventional phacoemulsification cataract surgery with in-the-bag implantation of the IOL in the contralateral eye (control eye) in random order. The same surgeon (R.M.) performed all cataract surgeries in a standardized fashion between June 2006 and October 2006. The surgical technique with combined primary posterior CCC and posterior optic buttonholing has been described in detail.24–26 A temporal 3.0 posterior limbal incision was created. An anterior CCC, hydrodissection, and phacoemulsification of the nucleus were followed by coaxial cortical remnant aspiration and biaxial lens fiber peeling. The anterior segment was filled with sodium hyaluronate 1.0% (Healon) to allow the remaining peripheral anterior capsule to settle on the posterior capsule and flatten the central posterior capsule. As a result, the capsule fornix collapsed and both capsules formed a common flat diaphragm. Following the outlines of the anterior CCC, a well-centered 4.5 mm to 5.0 mm primary posterior CCC was created. After the central capsule flap was removed from the eye, the ophthalmic viscosurgical device (OVD) was gently injected beneath the peripheral ring of residual posterior capsule to separate it from the underlying vitreous surface. When this was completed along the entire circumference, the anterior segment was prepared for IOL implantation. The central chamber was deepened and the nasal capsule fornix extended with OVD to take up the leading IOL haptic. The tip of the leading IOL haptic was guided into the nasal capsular bag fornix, and the optic and trailing haptic were rotated into the bag. Using gentle downward pressure, the optic was entrapped in the primary posterior CCC. The OVD was then aspirated from the anterior chamber and capsular bag fornix using low flow and vacuum settings. As the posterior capsule was firmly pressed onto the anterior optic surface, the optic–capsule diaphragm hermetically sealed the posterior segment and no OVD was allowed to access the anterior chamber from the retrolental space during the maneuver. Next, the incisions were hydrated and the globe was pressurized. The eye was left unpatched. All patients received diclofenac sodium (Voltaren) and prednisolone acetate (Ultracortenol) eyedrops 4 times daily for 4 weeks postoperatively. The anterior chamber depth (ACD), defined as the distance from the posterior corneal surface to the anterior IOL surface, was measured after a minimum of 6 months postoperatively with the ACMaster (Zeiss Meditec AG) based on the principal of PCI biometry. The principle of the dual-beam version of PCI and its use in phakic and pseudophakic eyes has been described.27–29 This technique has been used to perform accurate biometry in pseudophakic eyes with a precision of 4 mm for measuring the ACD and an axial resolution of 10 mm.30–32 The PCI device measures the ACD parallel to the optical axis of the eye and is insensitive to longitudinal eye movements during measurements. The eye being measured is the fixating eye, which prevents interference from convergence movements during measurement. Baseline measurements were performed with the patient fixating on an internal target collimated to infinity with the eye being measured. The eye was measured with the patient fixating on the target at optical infinity; 5 ACD measurements were taken. To assess the effect of maximum ciliary muscle contraction, 2 drops of pilocarpine 2% were instilled into the conjunctival sac of the examined eye at 5-minute intervals. Thirty minutes after the first application, the ACD was measured again. After a washout period of 1 week, the ACD measurements were taken again under
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cycloplegic conditions using cyclopentolate 1%; the protocol of administration and measurements were identical to those for pilocarpine application. A previous study of another nonaccommodating 1-piece foldable IOL (Acrysof SA60AT, Alcon Laboratories, Inc.)33 found the standard deviation (SD) of pilocarpine-induced IOL movement to be 125 mm. For this variability, it was determined that a sample size of 18 eyes would be needed to detect IOL movement of 175 mm (approximately equivalent to 0.25 D refractive change in the spectacle plane) with a power of 80% at the 0.05 level of significance. To compare the means of the change in the ACD (baseline versus pilocarpine), the paired Student t test was used. The ACD and IOL movement data are presented as the median value G SD and range. The influence of baseline ACD and change in ACD (ie, IOL movement under pilocarpine) was assessed using the Pearson correlation analysis. A P value of 0.05 or less was considered statistically significant.
Table 1. Anterior chamber depth under different conditions.
ACD (mm) Baseline Median G SD Mean Range Pilocarpine Median G SD Mean Range Cyclopentolate Median G SD Mean Range
P Value
POBH
IB
4.864 G 0.347 4.788 4.211, 5.404
4.724 G 0.300 4.700 4.160, 5.140
.12
4.921 G 0.308 4.893 4.324, 5.427
4.869 G 0.356 4.811 4.149, 5.523
.77
4.904 G 0.303 4.879 4.398, 5.439
4.807 G 0.273 4.776 4.395, 5.192
.40
ACD Z anterior chamber depth; IB Z in the bag; POBH Z posterior optic buttonholing
RESULTS The study enrolled 40 eyes of 20 patients. The mean age of the 13 women (65%) and 7 men (35%) was 77 years G 8 (SD) (range 55 to 88 years). The mean postoperative follow-up was 9.1 G 1.4 month (range 6 to 10 months). One patient was excluded postoperatively because the PCI measurements under pilocarpine were not possible in the control eye for unknown reasons. No intraoperative complications occurred. The median postoperative spherical equivalent was 1.38 G 1.25 D (range 4.00 to 0.50 D) in study eyes and 1.13 G 1.22 D (range 3.88 to 0.25 D) in control eyes. There was no significant difference between the groups (PZ.13). The median target refraction was 0.64 G 1.21 D (range 3.98 to 0.26 D) in study eyes and 0.53 G 1.10 D (range 3.39 to 0.20 D) in control eyes. Table 1 shows the ACD measurements under the various conditions. There was no significant difference in the median postoperative ACD between study eyes and control eyes (PZ.12) (Figure 1). After application of pilocarpine, a statistically significant backward IOL shift was detected in both groups of eyes; the mean shift was C78 G 78 mm in study eyes and C118 G 117 mm in control eyes (both P!.05) (Figure 2). There was no significant difference in pilocarpine-induced IOL shift between the 2 groups of eyes (PZ.19). The ACD measurements under cyclopentolate showed almost no IOL movement in study eyes (mean C20 G 26 mm; PZ.54) or in control eyes (mean C23 G 46 mm; PZ.87) (PZ.83 between eyes). There was no significant correlation between baseline ACD and IOL shift under pilocarpine-induced ciliary muscle contraction (r2 Z 0.29, PZ.29 in study eyes; r2 Z 0.30, PZ0.27 in control eyes). DISCUSSION This study showed a slight significant backward IOL shift in eyes with primary posterior CCC and posterior
optic buttonholing during pharmacologically stimulated ciliary muscle contraction with pilocarpine. Compared with IOLs implanted in the bag, no significant difference in IOL shift was detected. In the past, studies of monofocal nonaccommodating and of so-called accommodating IOLs were performed to gain a better understanding of the interplay between the ciliary body–capsular bag–IOL during pseudophakic accommodation or to assess the accommodative potential of an IOL. With conventional IOLs, varying results after near stimulus–driven ciliary muscle stimulation or pharmacologic stimulation with pilocarpine have been reported. Using optical pachymetry, Hardman Lea et al.34 observed a maximum forward IOL shift of 0.25 mm induced by pilocarpine. Using ultrasound, _ 35 found a forward shift Lesiewska-Junk and Ka1uzny of 0.42 mm in young pseudophakic patients while
Figure 1. Anterior chamber depth at baseline. Boxes show the interquartile range, whiskers the minimum and maximum (IB Z in the bag; POBH Z posterior optic buttonholing).
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Figure 2. Pilocarpine-induced IOL shift in pseudophakic eyes after cataract surgery assessed with PCI. Positive values indicate a backward shift, negative values a forward shift of the IOL. Boxes show the interquartile range, whiskers the minimum and maximum (IB Z in the bag; IOL Z intraocular lens; POBH Z posterior optic buttonholing).
accommodating at near. In another study, Niessen et al.36 found a forward shift of 0.18 mm. However, the reproducibility of the measurement methods used in these studies was poor. Using the high-precision PCI method, we recently showed that a plate-haptic IOL (AA4203VF, Staar Surgical Co.) had slight forward movement ( 162 mm).37 The 3-piece IOLs did not shift forward but shifted slightly backward; the mean was 56 mm for the MC 220 PMMA IOL (Dr. Schmidt Intraocularlinsen GmbH), C37 mm for the AR40 Sensar IOL (Allergan, Inc.), and C156 mm for the Acrysof MA60BM IOL (Alcon Laboratories, Inc.).37 The 1-piece Acrysof SA60AT foldable IOL was found to shift slightly backward by C25 mm during pilocarpine-induced ciliary muscle contraction.33 With a 20.0 D optic IOL, axial optic movement of approximately 720 mm corresponds to a 1.00 D change in refraction38,39; thus, the shifts detected are too small to provide relevant accommodation. Currently available accommodating IOLs should transform the forces of the ciliary body during accommodation into a forward shift of the IOL optic (optic-shift concept). To achieve an accommodative amplitude of 2.90 D, which would result in a reading distance of 35 cm, an anterior IOL shift of 2.2 mm would be needed, assuming an IOL power of 20.00 D.40 Until now, 3 presumably accommodating IOLs have been commercially available: the Biocomfold (Morcher GmbH), the 1CU (Human Optics AG), and the AT-45 Crystalens (Eyonics, Inc.). Summarizing the results of several nonrandomized trials using pharmacologic stimulation of the ciliary muscle with pilocarpine, the IOL shift varied with different
measurement techniques. Most studies of the 1CU IOL41–45 and the Biocomfold IOL37 found a forward shift of less than 700 mm in nearly all patients, which equals less than 1.00 D of accommodative amplitude at the spectacle plane. The IOL shift results of the AT-45 Crystalens IOL are controversial (slight forward shift46,47 and minimal backward shift48). Only 4 randomized controlled studies that evaluated pilocarpine-induced IOL shift found that accommodating IOLs were associated with significantly greater anterior IOL shift than control monofocal IOLs (1CU: 370 mm,49 820 mm,50 220 mm;51 Biocomfold: 710 mm52). However, no study found forward movement of more than 1.0 mm and the amount of movement was variable among patients. One limiting factor of IOL shift during accommodation through force transmission from the ciliary muscle to the lens via the zonular fibers (Helmholtz theory11) or through changes in vitreous pressure (Coleman theory12) could be capsule fibrosis. The fibrosis stiffens the capsular bag, causing a “walled in” IOL and thereby restricting axial movement of the optic. Therefore, to minimize constricting fibrosis and to provide a more flexible IOL optic, a primary posterior CCC with consequent posterior optic buttonholing was performed in 1 eye in the present study. In our study, IOL shift was measured using PCI, which enables precise measurement of very small changes. As expected for a standard IOL design, the IOL shift was very small and variable between patients. There was no difference between eyes with posterior optic buttonholing (study eyes) and eyes with conventional in-the-bag IOL implantation (control eyes). There was a small backward shift of C78 mm in study eyes and C118 mm in control eyes under pilocarpine and of C20 mm and C23 mm, respectively, under cyclopentolate. Although we have shown previously that pilocarpine acts physiologically in young phakic subjects,53 it seems to be a super stimulus in presbyopic and pseudophakic subjects53,54 when comparing pilocarpine-induced accommodation with voluntary near-point fixation. Therefore, although IOL movement may be overestimated with pilocarpine use, pilocarpine is still useful in the evaluation of the accommodative potential of an IOL. The same direction of shift found with ciliary muscle contraction and relaxation was previously observed with other IOLs37 and could possibly be explained by the fact that the IOL is in a slightly posterior vaulted configuration after completion of capsular bag shrinkage or in the posterior optic buttonholing position, respectively. Under pilocarpine-induced ciliary muscle contraction, there may be some direct pressure of the ciliary body on the haptic ends, causing increased vaulting that pushes the optic backward concomitant
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with a slight forward movement of the apex of the ciliary muscle. This would result in a net slight backward movement of the optic. Under cyclopentolate, the ciliary muscle apex rotates backward, causing the entire IOL–capsule complex to move backward. The backward IOL shift in both groups under pharmacologic stimulation of accommodation also reflects the failure of the optic-shift principle in providing clinically significant IOL movement in pseudophakic eyes (inconsistence of the hydraulic suspension theory of accommodation of Coleman12). The negligible small amount of mean IOL shift despite reduced fibrosis in the posterior optic buttonholing group shows that no optic shift movement during accommodation can be expected with this technique. This is consistent with observations in a study by Cleary et al.55 in which another fibrosisreducing procedure, the bag-in-the-lens concept, also led to an insignificant small forward IOL shift during pilocarpine stimulation. The more pronounced backward movement of the IOL in the posterior optic buttonholing group led to a (clinically irrelevant) disaccommodation compared with that of conventional in-the-bag fixated IOLs. However, the IOLs in this study are nonaccommodating; using accommodating IOLs with a specific design and haptics with flexible hinges may have led to a more pronounced IOL optic shift. To conclude, pilocarpine-induced ciliary muscle contraction after implantation of a nonaccommodating 3-piece IOL after cataract surgery with combined posterior capsulorrhexis and posterior optic buttonholing led to a slight significant backward IOL shift and thus to disaccommodation. The detected IOL shift did not differ significantly from the shift of in-the-bag IOLs. WHAT WAS KNOWN Accommodating IOLs based on the focus-shift principle and designed to provide good distance, intermediate, and near visual acuity have not shown clinically relevant movement during pilocarpine-induced ciliary muscle stimulation. The removal of the posterior capsule with a primary posterior CCC combined with posterior optic buttonholing was found to reduce capsule fibrosis, which is considered to limit axial IOL movement. WHAT THIS PAPER ADDS Posterior optic buttonholing of a 3-piece IOL showed no accommodative advantage over a conventional in-thebag fixation. This provides further evidence that the axial IOL optic movement is insignificant and fails to produce significant focus-shift-induced accommodation.
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OTHER CITED MATERIAL A. Menapace R. Cataract surgery with combined primary posterior continuous curvilinear capsulorhexis (PPCCC) and posterior buttonholing (POBH) in comparison to conventional in the bag intraocular lens (IOL) implantation. ISRCTN35593439, 2007. Available at: http://www.controlled-trials.com/isrctn/pf/ 35593439. Accessed July 3, 2012
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First author: Christina Leydolt, MD Department of Ophthalmology, Medical University of Vienna, Austria